Fluorescent lamps (also known as gas discharge lamps) economically illuminate an area. Due to the unique operating characteristics of fluorescent lamps, the lamps must be powered by a ballast. Electronic ballasts provide a very efficient method of powering fluorescent lamps.
Generally, when power factor correction is required, an electronic ballast has a boost front-end for converting AC (alternating current) voltage from an AC power source into a DC (direct current) voltage which has a value greater than the peak voltage of the AC power source. An inverter then converts the DC into high frequency AC power.
It is highly desirable that the light level of the fluorescent lamps be adjustable. However, since the fluorescent lamps are energized by a ballast, designing a dimming circuit which provides adjustment of the light level is not straightforward.
Additionally, the dimming control itself is usually located remotely from the ballast. If the dimming control wires possess a potential different from that of the AC power lines, then the wires connecting the dimming control to the ballast must be routed through a conduit separate from the power lines, as required by Underwriters Laboratory. The requirement of a separate additional conduit makes installation of dimming ballasts very expensive.